Rotary heat exchanger with a chain drive



June 4, 1968 T s. ABBOTT 3,386,718

ROTARY HEAT EXCHANGER WITH A CHAIN DRIVE Filed Aug. 8, 1966 EWMW United States Patent 3,386,718 ROTARY HEAT EXCHANGER WITH A CHAIN DRIVE Thomson S. Abbott, Milwaukee, Wis., assiguor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Aug. 8, 1966, Ser. No. 571,021 2 Claims. (Cl. 263-33) ABSTRACT OF THE DISCLOSURE A rotary kiln is disclosed which is provided with an assembly for rotating the kiln shell about a generally horizontal axis. The assembly includes a chain looped around the shell and a sprocket external of the chain loop but engaging the chain to turn the shell. The chain comprises a first series of links and a second series of links arranged alternately with the links of the first series. The links of the first series are each rigidly connected to the shell and the links of the second series are articulately connected to the links of the first series. The chain assembly is there fore rigidly attached to the kiln shell around the entire periphery of the shell and also articulately conforms to the shape of the shell as it is distorted due to thermal and other stresses applied to the shell.

This invention relates to apparatus having a rotatable cylindrical shell and in particular to rotary kilns provided with a drive for turning the cylindrical shell about its central axis.

For many years, rotary kilns have been driven to turn about their central axis in a manner such as shown in FIG. 1 of US. Patent 2,728,146. As shown in that patent, an annular gear has in the past been mounted around the outer circumference of the kiln and a power driven pinion is provided to engage the annular gear and turn the gear and shell. It has also been proposed in the past to provide an endless chain around the annular gear and a driven sprocket, as shown in US. Patents 2,878,004 and 3,042,208.

Rotary kilns are presently being built with much larger diameters than have been popular in the past. Where, in the past, it was the practice to provide several kilns of feet diameter, it is now the practice to supply a single kiln having a diameter of 20 or more feet. Annular gears mounted around shells of such large diameter are expensive, heavy, difficult to mount and because of their greater diameter, they are more subject to thermal stresses and distortion induced by high temperatures and temperature variations within the kiln.

Among the solutions to such problems proposed by the prior art are those disclosed in U.S. Patents 2,605,646 and 2,999,396. Both of these patents disclose annular gears having an inner diameter larger than the outer diameter of the kiln and therefore the annular gear is spaced radially outward from the kiln. Such gears are mounted on the kiln by outwardly projecting supports spaced about the circumference of the kiln. Although such spaced gears are heated somewhat less than the gears disclosed in the patents referred to in previous paragraphs, they are, for very large kilns, still expensive, heavy, difiicult to mount and the distortion of the kiln within the circle defined by the spaced gear results in stress being applied and concentrated on the circumferentially spaced and outwardly projecting supports.

The present invention is directed to a new and improved apparatus of the type described and to solving the problerns that have been described as being associated with prior designs and constructions of such apparatus. It is among the objects of the present invention to provide an apparatus, having a rotatable shell subject to stress and distortion, with a less expensive but improved drive for rotating the shell about its central axis that also accommodates thermally induced distortion without applying metal fatiguing stress to parts of the drive system.

According to a preferred embodiment of the present invention, an annular flange is secured to the outer circumference of the kiln. An endless roller chain is arranged around the outer periphery of the flange and connected to the flange to conform thereto as the flange is distorted by thermally induced stresses. A motor driven sprocket, having a plurality of radially projecting teeth, is spaced from the kiln and flange and arranged with the sprocket axis parallel to the kiln axis. Sprocket teeth projecting toward the kiln shell engage the chain to rotate the kiln shell upon rotation of the driving sprocket. A second chain and sprocket such as has been described may be axially spaced from a first such assembly, with both sprockets mounted on a common motor driven shaft, in order to divide the torque transmitted to the kiln, between the two chains.

Other objects of the invention and how they are attained will become apparent as the following description is read in view of the attached drawing, wherein:

FIG. 1 is a partial side elevation of a rotary kiln incorporating a preferred form of the present invention; and

FIG. 2 is a view in cross section taken along the line IIII in FIG. 1.

Referring to FIG. 1 of the drawing, the apparatus shown comprises an elongated cylindrical shell assembly 3 having a pair of axially spaced annular riding rings 4 and 5. These annular rings 4, 5 may be supported on rollers 6, 'i journaled in bearings S, 9 and 10, 11, respectively, for rotation of shell 3 about its own central axis.

Referring to FIG. 2 of the drawing, the shell assembly includes an annular flange 29 which has a peripheral surface Zita. Flange 20 is mounted on the outer circumference of shell 3 and secured thereto in any suitable manner, as for example by welding. An endless roller chain 21 is arranged around the outer periphery of flange 20. The chain 21 comprises a plurality of links '22. The links are arranged in pairs with the links of each pair being parallel to each other. The links of alternate pairs in the chain are called inside links 23 and outside links 24. The terms are conventional and arise from the way the ends of adjacent links overlap. That is, the ends of a pair of parallel links 24 overlap and are outward of the overlapped ends of an adjacent pair of parallel links 23. The links 24 are therefore called outside links and the links 23 are called inside links. A pin 25 passes through the ends of a pair of outside links 24 and a pair of overlapped inside links 23 and a roller 26 placed between the ends of the inside links. The chain thus far described and the terminology used to describe it is conventional according to the American Standards Association as explained on pages 50 5 and 506 in the book Machine Design by Hyland and Hommers, published by McGraw-Hill Book Company, Inc, 1937.

The chain 21 is shown as being connected to flange 20 by providing a bracket portion 30 projecting radially inward from each of the inside links 23. The brackets 30 are each secured to the flange 20 by a pair of bolts 31.

As shown in FIG. 1, a second chain 21a may be mounted on a second flange 20:: (see FIG. 2) in axially spaced relation to flange 20 and chain 21.

With further reference to FIG. 1, a driving assembly 34 is shown comprising a motor 35 mounted on a pedestal 36. The motor 35 drives a shaft 37 parallel to shell 3 and journaled in bearings 38 mounted upon a support 39 which in turn may be mounted on the pedestal 36. A pair of sprockets 40, 41 are mounted on shaft 37 and are axially spaced from each other to be in the respective radial planes defined by the chains 21, 21a. The sprockets 4t 41 may be keyed to shaft 37 in any suitable manner (not shown). As shown in FIG. 2, sprocket 40 is provided with radially outward projecting teeth 42. The alignment of sprocket 49 is such that as teeth 42 are pointed toward shell 3 during rotation of sprocket 40, such teeth engage rollers 26 of chain 21 by projecting into a space 43 defined between adjacent rollers 26 and between an axially aligned pair of inside links 23 or outside links 24.

A second driving assembly 34a may be provided and arranged as shown in FIG. 2. The assembly 34:: may be identical to the described assembly 34.

In the operation of the described apparatus, motor 35 is energized by suitable means (not shown) to turn shaft 37 clockwise as viewed in FIG. 2. Shaft 37 turns sprocket 4% to turn teeth 4.2 toward shell 3 and project such tech into space 43 where the rollers 26 of chain 21 are engaged and the assembly of chain 21, flange 2t) and shell 3 is thereby rotated counterclockwise as viewed in FIG. 2. The pins 25 provide an articulate connection between adjacent links of the chain. The chain therefore continuously conforms to the circumferential shape of the peripheral surface 20a without slack and despite thermally induced distortion that may cause flange 29 to become out-ofround, and without applying any metal fatigue producing stress to the chain 21. The aforesaid achievements are accomplished, in the manner described, with a unique application and adaptation of stanrard chain links and therefore provides a relatively inexpensive, easy to assemble arrangement of easily handled component parts (i.e., the links). Thus, it has been shown how the objects of the present invention have been attained in .a preferred manner. However, modifications and equivalents of the disclosed concepts such as readily occur to those skilled in the art (for example, substituting block chain for the roller chain 21) are intended to be included in the scope of this invention. Thus, the scope of this invention is intended to be limited only by the scope of the claims such as are, or may hereafter be, appended hereto.

The embodiments of the invention in which an exclusive property or-privilege is claimed are defined as follows:

1. In an apparatus having a generally horizontal cylindrical shell assembly subject to stress and distortion supported on horizontally spaced supports to rotate about a and means for rotating said shell assembly about the central axis thereof, comprising, an endless chain arranged around said peripheral surface and between said horizontally spaced supports with said chain connected to said shell assembly to conform to circumferential shape of said surface along the entire circumference of said chain, and a rotatable sprocket having a plurality of radially projecting teeth, said sprocket being spaced away from said shell assembly and aligned relative to said shell assembly with the axis of said sprocket parallel to the axis of rotation of said shell assembly and with teeth of said plurality of teeth that project from said sprocket toward said shell assembly engaging said chain to rotate said shell assembly upon rotation of said sprocket, said chain comprising a first series of links and a second series of links arranged alternately with the links of said first series, said first series of links each having a portion projecting radially inward and rigidly attached to said shell assembly, and said second series of links being spaced radially outward from said shell assembly and articulately connected to adjacent links of said first series whereby said links of the second series are movable relative to said shell and said links of the first series to secure said chain to said shell with said chain having a shape conforming to the circumferential shape of said shell.

2, In an apparatus according to claim It, said shell assembly having an annular flange about the shell with said flange projecting radially outward of said shell, a peripheral surface defining the outer circumference of said flange, said chain being arranged around said peripheral surface and said radially inward projecting portion of each link of said first series being attached to said flange to support said links of the second series spaced radially outward of the outer circumference of said flange.

References Cited UNITED STATES PATENTS 672,065 4/1901 Lawrence 26333 X 2,296,791 9/1942 Keener et al. 263-7 2,455,531 12/1948 Stroman 26333 X 3,108,488 10/1963 Huszar 74-465 IOHN I. CAMBY, Acting Primary Examiner. 

